Sound Isolation Solutions For Ceilings and Floors

Unfortunately, most footfall noise complaints are directed to the neighbor above so treating the ceiling is typically the only reasonable option. This in no way means that your goal to isolate impact noise is unattainable, but your options in doing so are seriously limited. The energy from structure borne noise, ie impact noise, footfall noise, moving furniture, is more intense and more difficult to isolate than basic airborne noise. Flanking (vibrations passing from one material to the next) is more prevalent when you treat the ceiling rather than the floor. This is because you are treating the bottom side of the ceiling after the sound has passed through the structure rather than treating the floor before the sound reaches the structure. Because of this your attempt to isolate this type of sound will require more work.

What Will Work

Decoupling: Decoupling will always provide superior isolation over all other methods or products. The most cost efficient and most effective way to decouple your ceiling drywall is the use of resilient sound clips. Please note that this option will require the demolition of your existing drywall ceiling to attach the clips directly to the joists. This is a requirement to avoid something known as the triple leaf effect which, if ignored, will reduce performance of the clips significantly.

The IIC rating (rating measuring isolation of impact noise) of a GenieClip system on wood joists with double layer drywall installed is IIC 51. This IIC rating with wood or tile flooring is roughly a 400% gain over having a non-decoupled ceiling. To compare with something familiar, most carpet with carpet pad installations over wood framing will achieve an IIC rating around or slightly below 50. Reaching an IIC rating above 50 will resolve the majority of footfall noise complaints. To take this a step further, you can apply Green Glue Compound in between the double layer drywall installed on your clip system. This will give you a boost up into the mid-50's and higher which will result in very little sound transfer from impact noise above.

What Will Not Work

Damping: Applying Green Glue Compound to your ceiling to isolate impact noise is right on the border between effective and not effective. There are currently no official IIC tests on Green Glue Compound so it is difficult to estimate exactly how well it can isolate impact noise in any situation, let alone the bottom side of a ceiling. Simply adding Green Glue Compound to your ceiling will provide a noticeable improvement, but likely not enough of an improvement to satisfy your expectations.

Mass: Your ceiling is significantly heavy and well sealed as it is. Adding more mass with products like mass loaded vinyl, several layers of drywall, or any other random heavy product, will not provide a noticeable improvement when attempting to isolate impact noise. This method might improve the STC rating of the ceiling by a little, but that will only improve your isolation of airborne noise with no effect on isolating impact noise.

Resilient Channel/Furring Strips: Resilient channel is a form of decoupling, but unlike a resilient sound clip system with furring hat channel, resilient channel does not decouple the drywall from the structure enough to reduce the IIC rating of the ceiling significantly. Resilient channel performs well for isolating airborne noise when installed properly which is directly to the joists without short circuits. The energy from impact noise is too much for a resilient channel system to handle to achieve a rating that will satisfy the majority of customers. The IIC rating for a resilient channel system on a normal ceiling is about equal to using Green Glue Compound on your ceiling.

Triple Leaf Effect: We have established that decoupling is the only real way to isolate impact noise, but you must careful as to not create a triple leaf scenario by installing clips over existing drywall or plaster. A triple leaf (sub-floor is the first leaf, layer attached to joists is the second leaf, layer attached to channel is the third leaf) will reduce the performance of a resilient sound clip system by about 10 STC points. The reduction of the IIC rating is not as dramatic, but we still strongly recommend avoiding a triple leaf scenario. If a triple leaf is unavoidable then you can help lessen the degradation by installing R-6 or R-8 insulation between the existing layer of drywall and the furring channel.

Insulation: Insulation will provide no benefit to isolating impact and footfall noise. Insulation should be included in every sound isolation project, but it should never be used as the sole method of isolating sound. It will provide minimal improvement in isolating airborne noise and absolutely nothing for isolating impact noise.

What You Will Need For the Job

• Resilient Sound Clips: We recommend the GenieClip for the highest IIC rating possible.
• Furring Hat Channel: This can be purchased online through our site or locally for much cheaper at any drywall distributor in the United States. Channel currently sells for about .40 cents per linear foot depending on the market and constantly fluctuating steel prices.
• Double Layer Drywall: We strongly recommend using double layer drywall on any clip system. The extra cost is minimal overall and the increase in performance is more than double.
• Green Glue Sealant: Clip systems can only perform well if they are sealed well. The ceiling drywall should be cut back 1/4" from the perimeter walls and caulked using a flexible acoustic caulk. Any other gaps remaining in the ceiling after texture must be sealed with an acoustic caulk.

Possible Additions

• Green Glue Compound: You can apply Green Glue Compound between the double layer drywall attached to your clip system or against the bottom side of your sub-floor. Both methods would provide a significant improvement to any clip system. Green Glue Compound alone likely will not decrease the transfer of footfall noise enough to satisfy your expectations, but this product is definitely recommended to provide a nice boost when used in conjunction with a resilient sound clip system.

Treating sound problems at the source is always the most effective way to reduce sound transfer. Doing so will limit sound flanking (vibrations passing from one material to the next) throughout the structure. The ability to treat the floor really opens up your options to lower cost products and less drastic installation compared to resilient sound clips.

What Will Work

Rubber Underlayment: Rubber underlayment is specifically designed to increase the IIC rating and STC rating of a floor to meet or exceed building code requirements. The most common rubber underlayment thickness installed is 5 MM (~1/4"). Similarly to Green Glue Compound, rubber underlayment performs best when installed between two rigid surfaces. The sub-floor will act as one rigid surface and the finish flooring acting as the second rigid surface, whether it is tile, hardwood, laminate, or particle board with vinyl, will create a sandwich of materials with a flexible core. Rubber underlayment will always perform best installed over concrete, but whether the sub-floor is concrete or wood the IIC rating can easily reach the IIC 50+ range depending on the thickness of the rubber. Carpet and carpet pad can be installed over the top of the underlayment to increase the IIC rating of the floor into the 70's - which is essentially a total isolation of impact noise. Our QuietGround 250 (5 MM) underlayment is recommended for most installations, especially if the ceiling beneath is resilient. The QuietGround 375 (10 MM) will provide a significant increase in performance over the QG250 pushing the IIC rating into the mid-50's to high-50's IIC ratings.

Green Glue Compound: Treating the floor with Green Glue Compound will definitely decrease the impact noise sound transmission between floors. There is currently not any available IIC tests for Green Glue Compound in a floor so there is no way to know for sure how well it truly performs in a floor installation. However, based on the experience of our customers, Green Glue Compound compressed between a new 1/2" or 5/8" layer of sub-floor will definitely cut down on impact noise transfer as well as airborne noise. For the time being, we do recommend using Green Glue Compound in floors and even possibly in conjunction with rubber underlayment overlaying the new sub-floor with Green Glue Compound. But the glaring omission of IIC tests from the Green Glue Compound manufacturer should be taken into consideration as a sign that maybe the actual IIC rating is not improved significantly by adding Green Glue Compound.

Carpet with Carpet Pad: Basic carpet with carpet pad might just solve your problem without having to buy any sound isolation products at all. Carpet with pad will not do anything to isolate airborne noise, but the performance of carpet with a thick pad is nearly equal to a rubber underlayment installed under a wood or tile floor.

What Will Not Work

Mass: Floors have a significant amount of mass already so minor additions of mass, ie 1 LB MLV, extra layers of sub-floor, cement board, will not improve the IIC rating of the floor. Besides, the main objective in isolating impact noise is increasing resilience beneath the flooring. Adding mass will not aid in adding resilience. It makes sense that MLV would help in isolating impact noise because it is a semi-flexible material. However, based on customer reviews, only the 2 LB MLV has proven to be effective at reducing the transfer of impact noise. This is likely a result of the increased thickness of the 2 LB MLV vs. the 1 LB MLV rather than the increase in weight.

Acoustic Cork: Cork materials, unless incredibly thick (1" +), will not significantly improve the IIC rating of a floor. Cork has been tested to perform only about a third as well as rubber underlayment of the same thickness. It has remained a popular product largely because of the cheap price tag and partly because of the implied environmentally friendly aspect. We have had some customers in the past choose to use cork over rubber with the argument that it is so much cheaper than the rubber. Saving a couple hundred dollars on a small project does not really add up to true savings if the product purchased does not actually work. A readily available product at Home Depot and Lowe's types stores usually referred to as sound board will not perform any worse than acoustic cork and would cost even less. So if the goal is to buy a cheap, light, and ineffective product then we would recommend sound board over any acoustic cork regardless of the cork manufacturers' claims in IIC performance.

Insulation: Insulation will provide no benefit to isolating impact and footfall noise. Insulation should be included in every sound isolation project, but it should never be used as the sole method of isolating sound. It will provide minimal improvement in isolating airborne noise and absolutely nothing for isolating impact noise.

What You Will Need For the Job

Option 1

• QuietGround Rubber Underlayment: We recommend the QuietGround 250 for most projects. With other versions though, clear cost savings with still a good increase in performance can be had with the QuietGround 125. And for supreme isolation of impact noise, the QuietGround 375 should definitely be considered.
• Seam Tape: Standard duct tape can be purchased from any hardware store.
• Acoustic Caulk: Any gaps in the floor and along the perimeter of the room must be sealed to reduce noise transfer and flanking. Sealing the sub-floor before installation of the rubber underlayment is recommended.

Option 2

• Green Glue Compound: The alternative to using rubber underlayment is the use of Green Glue Compound between the existing layer of sub-floor and a new layer of sub-floor. We recommend rubber underlayment, but Green Glue Compound does provide good enough results to satisfy most expectations.
• New Layer of Sub-Floor: Used to overlay the Green Glue Compound. The new layer of sub-floor can be 1/4" to 3/4" thick. The mass of the new layer of sub-floor will not affect the results much as the Green Glue Compound will be the product that is providing the largest performance increase.
• Acoustic Caulk: Any gaps in the floor and along the perimeter of the room must be sealed to reduce noise transfer and flanking. Sealing the sub-floor before installation of the Green Glue Compound and new layer of sub-floor is recommended.

Possible Additions

• Green Glue Compound with Rubber Underlayment: This option would involve combining both Green Glue Compound and rubber underlayment. Start by applying Green Glue Compound to the existing sub-foor and overlaying with a new layer of sub-floor. Then roll our QuietGround 250 or QuietGround 125 over the top and install the finished floor above that. This idea will cover a wider range of frequencies and will max out the IIC rating for your floor without major re-engineering.
• Flooring Adhesive: If your floor requires over 1,000 square feet of rubber underlayment, or if the flooring installed over the rubber is glued or mortared down, then the rubber underlayment must be glued down. We recommend using our GenieMat FAS with our QuietGround underlayment, but any polyurethane based adhesive will work just fine.

As noted above, treating sound problems at the source is always the most effective way to reduce sound transfer. Doing so will limit sound flanking (vibrations passing from one material to the next) throughout the structure. However, often only the ceiling is treatable either because neighbors are uninterested in your sound isolation project or an expensive flooring exists on the floor above you. So because of this, let's discuss how to treat your ceiling to isolate your airborne sound problems.

What Will Work

Decoupling: Decoupling will always provide superior isolation over all other methods or products. The most cost efficient and most effective way to decouple your ceiling drywall is the use of resilient sound clips. Please note that this option will require the demolition of your existing drywall ceiling to attach the clips directly to the joists. This is a requirement to avoid something known as the triple leaf effect which, if ignored, will reduce performance of the clips significantly.

When dealing with airborne noise, the STC and OITC ratings are what should be reviewed rather than the IIC ratings discussed above. The STC rating (rating measuring isolation of mid and high frequency noise) of a GenieClip system on wood joists with double layer drywall installed is STC 54. This STC rating with wood or tile flooring is roughly a 300% gain over having a non-decoupled ceiling. Reaching an STC rating above 50 will resolve the majority of airborne noise transfer complaints. Achieving a high STC rating in a ceiling is more difficult than in a wall. This is simply because the wall weighs less and is more resilient. A 50+ STC rating in a ceiling is significant whereas a 60+ STC rating in wall is significant.

Green Glue Compound: This is the best option in situations where you need to reduce sound transfer minimally and your only option is to overlay existing drywall. Green Glue Compound in walls will have a 50+ STC rating while the rating in ceilings is likely in the mid 40's STC. If you can remove your drywall and you are dead set on staying away from clip systems altogether, then consider applying Green Glue Compound sandwiched between a layer of drywall to the bottom side of your sub-floor as well as double layer drywall and Green Glue Compound on your joists. This will give you a noticeable boost which will bring your rating a little closer to the 50 STC rating.

What Will Not Work

Mass: Ceilings have a significant amount of mass already so minor additions of mass, ie 1 LB MLV, will not noticeably improve the STC rating of the ceiling. Because of the extreme mass already had by the ceiling, your efforts should be focused on introducing new sound isolation methods to the assembly to increase isolation. These methods of course being decoupling, damping, and absorption.

Resilient Channel/Furring Strips: Resilient channel and furring strips are simply not resilient enough to handle the mass of your ceiling. Both can provide a decent boost in performance at an extremely low price in walls, but resilient channel and furring strips are not considered good solutions for isolating airborne noise in a ceiling. Decoupling is great, but ceilings require more and the minimum would be a true resilient sound clip system.

Sound Board: Sound board used anywhere other than in a floor has as much benefit as adding a single layer of drywall. The only worthy attribute of sound board is that it provides a slight break in connection between the drywall and the framing. The improvement from this break is quickly lost due to the minimal mass of the sound board. So ultimately a layer of sound board will test as well as adding a layer of drywall.

Insulation Alone: We would never recommend leaving insulation out of the equation entirely, but please do not insulate your ceiling to isolate sound without including at least decoupling or damping in your isolation plan. Insulation only treats between the joists, which is important, but the the majority of the energy will attempt to transfer through your framing. Insulation does nothing to resolve this simple fact.

What You Will Need For the Job

Option 1

• Resilient Sound Clips: We recommend the GenieClip for the highest STC rating possible.
• Furring Hat Channel: This can be purchased online through our site or locally for much cheaper at any drywall distributor in the United States. Channel currently sells for about .40 cents per linear foot depending on the market and constantly fluctuating steel prices.
• Double Layer Drywall: We strongly recommend using double layer drywall on any clip system. The extra cost is minimal overall and the increase in performance is more than double.
• Green Glue Sealant: Clip systems can only perform well if they are sealed well. The ceiling drywall should be cut back 1/4" from the perimeter walls and caulked using a flexible acoustic caulk. Any other gaps remaining in the ceiling after texture must be sealed with an acoustic caulk.

Option 2

• Green Glue Compound: The lower performing option of the two, but definitely the less complicated installation. We recommend resilient sound clips, but Green Glue Compound does provide good enough results to satisfy lower expectations.
• New Layer of Drywall: If you have existing drywall then simply overlay with a new layer of 1/2" or 5/8". We recommend 5/8" to improve performance in isolating low frequencies, but either thickness will be fine.
• Acoustic Caulk: Any gaps in the ceiling and along the perimeter of the room must be sealed to reduce noise transfer and flanking. Sealing around outlet openings, light openings, and HVAC openings is required.

Possible Additions

• Green Glue Compound Against Bottom Side Of Sub-Floor: You can apply Green Glue Compound between the single or double layer drywall attached to the bottom side of your sub-floor. Make sure to seal any gaps around protrusions through the floor and the gaps created between the drywall and the sides of the joists.
• Insulation: Most ceilings, even in multi-family units, are not insulated. Blowing in insulation is cheap and easy to do with equipment that can be rented for free from home improvement stores. If your joists are exposed then install some cheap fiberglass batting - R-19 for almost every ceiling application.

As noted above, treating sound problems at the source is always the most effective way to reduce sound transfer. Doing so will limit sound flanking (vibrations passing from one material to the next) throughout the structure. Treating the floor to restrict sound transmission from the room below passing through your floor is a difficult task. If you are dealing with low levels of sound transmission such as speech, television noise, and basic day to day noise then you can still succeed.

What Will Work

Rubber Underlayment: Rubber underlayment is specifically designed to increase the IIC rating and STC rating of a floor to meet or exceed building code requirements. The most common rubber underlayment thickness installed is 5 MM (1/4"). Similarly to Green Glue Compound, rubber underlayment performs best when installed between two rigid surfaces. The sub-floor will act as one rigid surface and the finish flooring acting as the second rigid surface, whether it is tile, hardwood, laminate, or particle board with vinyl, will create a sandwich of materials with a flexible core. Rubber underlayment will always perform best installed over concrete, but whether the sub-floor is concrete or wood the STC rating will easily reach the high 40's STC range. Our QuietGround 250 (5 MM) underlayment is recommended for most installations. The QuietGround 375 (10 MM) will provide a significant increase in performance over the QG250 pushing the STC rating into the low-50's.

Green Glue Compound: Treating the floor with Green Glue Compound will definitely decrease the airborne noise sound transmission between floors. There is currently not any available STC tests for Green Glue Compound in a floor so there is no way to know for sure how well it truly performs in a floor installation. However, based on the experience of our customers, Green Glue Compound compressed between a new 1/2" or 5/8" layer of sub-floor has satisfied all expectations of isolating airborne noise as well as impact noise. For the time being, we do recommend using Green Glue Compound in floors and even possibly in conjunction with rubber underlayment overlaying the new sub-floor with Green Glue Compound. But the glaring omission of STC tests from the Green Glue Compound manufacturer should be taken into consideration as a sign that maybe the actual STC rating is not improved significantly by adding Green Glue Compound.

What Will Not Work

Mass: Floors have a significant amount of mass already so minor additions of mass, ie 1 LB MLV, extra layers of sub-floor, cement board, will not significantly improve the STC rating of the floor. However, based on customer reviews, the 2 LB MLV has proven to be effective at reducing the transfer of airborne and impact noise. This is likely a result of the increased thickness of the 2 LB MLV vs. the 1 LB MLV rather than the increase in weight alone.

Acoustic Cork: Cork materials, unless incredibly thick (1" +), will not significantly improve the STC rating of a floor. Cork has been tested to perform only about a third as well as rubber underlayment of the same thickness. It has remained a popular product largely because of the cheap price tag and partly because of the implied environmentally friendly aspect. We have had some customers in the past choose to use cork over rubber with the argument that it is so much cheaper than the rubber. Saving a couple hundred dollars on a small project does not really add up to true savings if the product purchased does not actually work. :) A readily available product at Home Depot and Lowe's types stores usually referred to as sound board will not perform any worse than acoustic cork and would cost even less. So if the goal is to buy a cheap, light, and ineffective product then we would recommend sound board over any acoustic cork regardless of the cork's manufacturer claims in STC performance.

Insulation: Insulation will provide little benefit to isolating airborne noise. Insulation should be included in every sound isolation project, but it should never be used as the sole method of isolating sound.

What You Will Need For the Job

Option 1

• QuietGround Rubber Underlayment: We recommend the QuietGround 250 for most projects. For supreme isolation of airborne noise using rubber underlayment, the QuietGround 375 should definitely be considered.
• Seam Tape: You can purchase the Light TotalMass Tape from our site or pick up some rolls of vinyl duct tape at a hardware store.
• Acoustic Caulk: Any gaps in the floor and along the perimeter of the room must be sealed to reduce noise transfer and flanking. Sealing the sub-floor before installation of the rubber underlayment is recommended.

Option 2

• Green Glue Compound: The alternative to using rubber underlayment is the use of Green Glue Compound between the existing layer of sub-floor and a new layer of sub-floor.
• New Layer of Sub-Floor: Used to overlay the Green Glue Compound. The new layer of sub-floor can be 1/4" to 3/4" thick. The mass of the new layer of sub-floor will not affect the results much as the Green Glue Compound will be the product that is providing the largest performance increase.
• Acoustic Caulk: Any gaps in the floor and along the perimeter of the room must be sealed to reduce noise transfer and flanking. Sealing the sub-floor before installation of the Green Glue Compound and new layer of sub-floor is recommended.

Possible Additions

• Green Glue Compound with Rubber Underlayment: This option would involve combining both Green Glue Compound and rubber underlayment. Start by applying Green Glue Compound to the existing sub-floor and overlaying with a new layer of sub-floor. Then roll our QuietGround 250 or QuietGround 125 over the top and install the finished floor above that. This idea will cover a wider range of frequencies and will nearly max out the STC rating for your floor without major re-engineering.
• Flooring Adhesive: If your floor requires over 1,000 square feet of rubber underlayment, or if the flooring installed over the rubber is glued or mortared down, then the rubber underlayment must be glued down. We recommend using GenieMat FAS with our QuietGround underlayment, but any polyurethane based adhesive will work just fine.